Reduced volume, high conductance process chamber

ABSTRACT

A vacuum processing apparatus including a process chamber having a plurality of pumping ports, and a plurality of pumping cells each connected to a respective pumping port of the plurality of pumping ports. The plurality of pumping ports is preferably located on a lower wall of the process chamber adjacent to a process chamber volume. A process chamber is also provided that includes a lower wall and a side wall, where the side wall has a height of about four inches. The vacuum processing apparatus further includes a chamber liner configured to displace open volume within the process chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to and claims priority to pendingapplication 60/399,380, entitled “Reduced volume, high conductanceprocess chamber,” Attorney docket no. 214458US6YA PROV, filed Jul. 31,2002. The contents of this application is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to process chambers used toprocess objects such as semiconductor wafers.

2. Discussion of the Background

The semiconductor manufacturing industry and the semiconductormanufacturing equipment industry represent multi-billion dollarindustries. Under conventional manufacturing processes, integratedcircuits are fabricated using very expensive machines. In mostintegrated circuit fabrication machines used today, one of the mostexpensive components is a process chamber.

The process chamber is typically a fairly large component with complexmachined features on many surfaces. In order to perform sufficientlyduring the manufacturing process, the process chamber must be clean andmust be capable of functioning in high vacuum and ultra high vacuumranges. In most cases, the process chamber is machined from a single,large billet of raw material. However, the use of a large billet of rawmaterial is expensive and most of this material is subsequently machinedaway when fabricating the part.

SUMMARY OF THE INVENTION

In an effort to provide an improved process chamber, the presentinvention provides an arrangement that generally reduces cost ofmanufacturing the process chamber, and reduces open volume within theprocess chamber thereby increasing conductance within the processchamber.

Accordingly, the present invention advantageously provides a plasmachamber including a lower wall and a side wall, where the side wall hasa height of at most about four inches.

Additionally, the present invention advantageously provides a plasmaapparatus including a plasma chamber having a plurality of pumpingports, and a plurality of pumping cells each connected to a respectivepumping port of the plurality of pumping ports.

The present invention further advantageously provides a method of makingan improved process chamber including the step of making the processchamber with a lower wall and a side wall, where the side wall has aheight of at most about four inches.

Furthermore, the present invention advantageously provides a method ofmaking an improved process chamber including the steps of providing aplurality of pumping ports in the process chamber, and connecting arespective pumping cell to each of the plurality of pumping ports.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will become readily apparent with reference to thefollowing detailed description, particularly when considered inconjunction with the accompanying drawings, in which:

FIG. 1 is a side, partial cross-sectional view of a plasma etchingapparatus having a plasma chamber according to an embodiment of thepresent invention;

FIG. 2 is a perspective view of the vacuum processing apparatus depictedin FIG. 1 according to an embodiment of the present invention;

FIGS. 3A-3D are top views of various pumping port configurations withrespect to a chuck assembly;

FIG. 4A is a side cross-sectional view of a plate stock used to form theprocess chamber according to a first embodiment of the presentinvention;

FIG. 4B is a side cross-sectional view of a process chamber formed usingthe plate stock of FIG. 4A;

FIG. 5A is a side cross-sectional view of a mold used to form a processchamber according to a second embodiment of the present invention;

FIG. 5B is a side cross-sectional view of the mold of FIG. 5A filledwith material used to form the process chamber according to the secondembodiment of the present invention;

FIG. 6A is an exploded perspective view of component parts of a processchamber according to a third embodiment of the present invention; and

FIG. 6B is an assembled side view of the component parts depicted inFIG. 6A.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 depicts a preferred embodiment of a vacuum processing apparatus10 according to the present invention. The vacuum processing apparatus10 includes a process chamber 20 that defines a processing environmentor process chamber volume 22, which is generally sealed from theenvironment outside of the process chamber 20. The process chamber 20can, for example, facilitate processing with or without a processingplasma. The process chamber 20 generally has a chuck assembly 30 mountedtherein. The chuck assembly 30 is configured to hold a substrate, suchas a semiconductor wafer or a liquid crystal display (LCD), during theprocessing operation. The process chamber 20 and the associated chuckassembly 30 can, for example, be configured for processing substrates ofdiameter 200 mm, 300 mm, and larger.

The process chamber 20 can further include an upper electrode assembly40 mounted opposite the chuck assembly 30. In an embodiment of thepresent invention, the upper electrode assembly 40 can be electricallybiased to facilitate the formation of plasma. Alternately, the upperelectrode assembly 40 is maintained at an electrical potentialequivalent to that of the processing chamber 20. For example, processingchamber 20 and the upper electrode assembly 40 can be electricallyconnected to ground potential. In another embodiment, upper electrodeassembly 40 can comprise an antenna.

The process chamber 20 has an upper wall 24, a lower wall 26, and a sidewall 28. The lower wall 26 and the side wall 28 are preferably formed ofa single unit of material. The process chamber 20 can, for example, bemade of plate stock having a thickness of about four inches. The platestock is preferably aluminum, such as aluminum 6061-T651 plate-stock,although other materials can be used. FIG. 4A depicts a cross-sectionalview of a solid piece of plate stock P having a thickness t of aboutfour inches. The plate stock can be machined to form a bottom section ofthe process chamber as depicted in FIG. 4B. FIG. 4B depicts across-sectional view of the machined bottom section of the processchamber having the lower wall 26 and side wall 28 having a height of atmost about four inches.

Alternatively, the bottom section of the process chamber can be formedin the manner depicted in FIGS. 5A and 5B. FIG. 5A depicts across-sectional view of a mold 100 used during a molding process to formthe bottom section of the process chamber. The mold 100 includes anupper mold 101 and a lower mold 103, which when joined together define acavity 102 therebetween that is generally of the shape of the bottomsection of the process chamber. The cavity 102 has an inlet 104 thatreceives the molten material used to form the bottom section of theprocess chamber. Molten material is injected within the inlet to fillthe cavity 102 as depicted in FIG. 5B, and then the molten material iscooled and solidified to form a rough product 106. The rough product 106is then removed from the mold 100 by separating the upper mold 101 andthe lower mold 103, and the rough product 106 is machined slightly toform the bottom section of the process chamber including the lower wall26 and side wall 28.

Alternatively, as shown in FIG. 6A, the bottom section of the processchamber can be formed by joining a plate 110, which forms the lowerwall, and a cylindrical part 112, which forms the side wall. FIG. 6Adepicts an exploded perspective view of the plate 110 and thecylindrical part 112. The cylindrical part 112 can be, for example, arolled cylinder (or rolled ring forging). The plate 110 and thecylindrical part 112 can be joined by welding or another process alongjoint 114, as depicted in FIG. 6B.

The upper wall 24 can be positioned on a top edge of the side wall 28 asdepicted in FIG. 1 and sealed thereto to act as a lid. The seal formedbetween the top edge of the side wall 28 and the upper wall 24 can benon-permanent, i.e. the seal is formed via an o-ring and an o-ringgroove formed in at least one of the side wall 28 and the upper wall 24.For example, fastening devices (not shown) extending through the upperwall 24 and into (threaded) receptors (not shown) within the side wall28 can be used to facilitate compression of the o-ring and the formationof a vacuum seal. Alternately, for example, the upper wall 24 and sidewall 28 can further comprise at least one hinge (not shown) and at leastone latch (not shown) to facilitate compression of the o-ring, whereinclosing the latch permits sealing the process chamber 20 and opening thelatch permits opening the process chamber 20, i.e. the upper wall 24serves as a process chamber lid.

FIGS. 1 and 2 depict a cross sectional view and a perspective view ofprocess chamber 20 and associated hardware, respectively. The upperelectrode 40 and (moveable) chuck assembly 30 are depicted, as well astwo pumping cells 60 attached to the chamber floor or lower wall 26. Theprocess chamber 20 can also include a slot valve (not shown) and robot(not shown) to transfer substrates into and out of process chamber 20,and place substrates on the chuck assembly 30. The slot valve and robotare located on a rear side of the process chamber 20.

The process chamber 20 has one or more pumping ports 50 that arepreferably located on a floor or lower wall 26 of the process chamber 20adjacent to a process chamber volume 22. One or more pumping cells 60are each connected to a respective pumping port 50. The pumping cells 60each preferably include a turbo molecular pump (or TMP) and agate-valve. The pumping cells can also include a butterfly valve,depending on the gate valve configuration and function. Theconfiguration of the process chamber 20 provides for the attachment ofany number of pumping cells 60 to pump gas from the process chambervolume 22 depending upon the process being performed and the geometry ofthe machine. The pumping ports 50 and pumping cells 60 can be providedat the bottom and/or top of the process chamber 20 as required. Theproximity of the pumping cells to the process chamber volume 22 can leadto a significant improvement in process chamber conductance and, hence,pumping speed at the substrate.

FIGS. 3A-3D are top views of various pumping port configurations withrespect to a chuck assembly 30. The various configurations in FIGS.3A-3D do not represent all the arrangements that are possible in view ofthe teachings of the present inventions.

In FIG. 3A, two pumping ports 50 are provided on a floor of the processchamber. The pumping ports 50 are not symmetrically positioned about thechuck assembly 30. In FIG. 3B, a single pumping port 50 is provided onthe floor of the process chamber adjacent one side of the chuck assembly30. In FIG. 3C, three pumping ports 50 are provided in a symmetricallyspaced arrangement about the chuck assembly 30. The three pumping portsof FIG. 3C are arranged in a triangular configuration, spaced, forexample, in the azimuthal coordinate every 120 degrees. In FIG. 3D, twopumping ports 50 are provided symmetrically spaced about a chuckassembly 30 on opposing sides thereof. Each of the pumping ports 50depicted in FIGS. 3A-3D are preferably connected to a respective pumpingcell 60, however, alternatively a pumping port 50 can be sealed using alid such that no pumping cell is connected to the pumping port if such apumping cell is unnecessary in any given process.

The vacuum processing apparatus 10 can comprise means for reducing anopen volume within the process chamber 20. For example, a chamber linercan be configured to displace the open volume within the process chamber20. FIG. 1 depicts a liner 25 on the upper wall 24, a liner 27 on thebottom wall 26, and a liner 29 on the side wall 28. The liners 25, 27,and 29 can, for example, reduce the size of the process chamber volume22 within the process chamber 20, thereby decreasing the residence timeof the vacuum processing apparatus 10. Alternate liners for use insidethe process chamber 20 can be configured to displace more chamber volumethan depicted in FIG. 1. The liners can also be configured to reduce theresidence time while displacing more volume. The liners reduce theresidence time of gas atoms/molecules within the processing volume 22 byreducing the volume size while maintaining the same pumping speed at theprocessing volume. The conductance of the processing chamber, as awhole, is improved due to the configuration wherein the vacuum pumps arelocated proximate the processing volume. Typically, the liners arephysically changed during chamber maintenance, however movable linersare possible but they may be disadvantageous due to the complexity andthe increased risk for particulate generation. If the liners arephysically changed, they are inserted in sleeves that rest on shelvesformed within the process chamber or among themselves without actualfastening devices. Alternately, fastening devices can be employed toaffix the liners to the chamber walls.

One novelty of the present invention is an improvement in pumping speedand residence time, while lowering the overall costs to fabricate thevacuum processing apparatus 10. Another novelty is the plethora ofoptions available in pump sizes and locations in the process chamber 20.Furthermore, the present invention advantageously provides for changesin chamber configurations to add or subtract pumping cells to an enditem machine as the process or program goals change over time. Dependingon the number and size of the pumping cells, the end item footprintsizes can vary from smaller than other machines to larger than othermachines.

The present invention provides several advantages over other processingmachine configurations. For example, the present invention providesnumerous options for pumping geometries. Additionally, the pumpingspeeds are improved and/or the present invention provides aconfiguration that allows for the use of smaller and cheaper pumpingcell parts. Furthermore, fabrication costs for the plasma chamber aregreatly reduced. In addition, the reduced volume chamber is moreenvironmentally friendly since less process gas is used.

The present invention further provides a method of making an improvedprocess chamber 20 including the steps of providing one or more pumpingports 50 in the process chamber 20, and connecting a respective pumpingcell 60 to each of the one or more pumping ports 50, for example, in themanner discussed above with reference to FIGS. 1 and 3A-3D. The methodpreferably further includes the step of making the process chamber 20 ofaluminum plate stock having a thickness of about four inches.

Several problems associated with other semiconductor processing machineconfigurations are improved in the present invention.

First, the cost of raw materials and machining required to fabricateother process chamber configurations is very high. Material sizes canrange up to thirty inches by thirty inches by twenty-four inches thick.A two-hundred millimeter chamber can cost $20,000-$30,000, or more, formaterial, machining and post processing. The present invention utilizesaluminum plate stock having a thickness of about four inches. Since thethickness of the raw material in the present invention is aboutone-sixth the thickness in other configurations, the milling depths inthe present invention are much less. Therefore, the parts are muchcheaper because the raw material is cheaper and the machining issimplified.

Secondly, the other configurations use large turbo molecular pumps (orTMPs) and associated gate valves. These parts are also very expensive.Large sized pumps are required to pump relatively large chamber volumes.In the present invention, the process chamber volume is less thanone-third the volume in other machines. The present invention uses afinite number of smaller TMPs and associated gate valves. The sum of thecost of the smaller individual parts can be less expensive than othermachine configurations with only one large TMP and gate valve.Additionally, in the present invention smaller backing pumps may be usedwith the smaller TMPs, thereby further reducing costs.

Thirdly, the pumping conductance in other machines tends to be poor. Inother configurations, a single pumping port is located on a side wall ofthe process chamber. The single pumping port is connected to a plenumchamber, which in turn is attached to the gate valve and TMP. Thispumping path is very tortuous and restricts the vacuum flowconsiderably. Accordingly, in other machines, the actual pumping speedsat the wafer are only a fraction (about 30% and less) of the ratedpumping speeds of the TMPs used. The present invention has greatlyimproved conductance. The residence time and conductance improvement ispossible because the chamber volume is reduced by a factor of three andgate valves and associated TMP(s) are located directly on the processchamber floor (or the sidewalls) adjacent to the process chamber volume,respectively. The improvement in conductance of the present inventionallows for (1) better pumping speeds, (2) the use of smaller and cheapervacuum components to obtain existing pumping speeds, or (3) both (1) and(2).

It should be noted that the exemplary embodiments depicted and describedherein set forth the preferred embodiments of the present invention, andare not meant to limit the scope of the claims hereto in any way. Thus,numerous modifications and variations of the present invention arepossible in light of the above teachings. It is therefore to beunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described herein.

1. A process chamber comprising a lower wall and a side wall, whereinsaid side wall has a height of at most about four inches.
 2. The processchamber according to claim 1, wherein said process chamber is made of asingle unit of plate stock having a thickness of about four inches. 3.The process chamber according to claim 2, wherein said plate stock isaluminum.
 4. The process chamber according to claim 1, wherein saidprocess chamber has at least one pumping port configured to receive apumping cell.
 5. The process chamber according to claim 1, wherein saidprocess chamber has a plurality of pumping ports each configured toreceive a pumping cell.
 6. The process chamber according to claim 5,wherein said plurality of pumping ports are located on said lower wallof said process chamber adjacent to a process chamber volume.
 7. Theprocess chamber according to claim 5, wherein three pumping ports areprovided on said lower wall of said process chamber symmetrically spacedabout a chuck assembly provided within said process chamber.
 8. Theprocess chamber according to claim 1, further comprising means forreducing open volume within said process chamber.
 9. The process chamberaccording to claim 8, wherein said means for reducing open volume is achamber liner configured to displace open volume within said processchamber.
 10. A vacuum processing apparatus comprising: a process chamberhaving a plurality of pumping ports; and a plurality of pumping cellseach connected to a respective pumping port of said plurality of pumpingports.
 11. The vacuum processing apparatus according to claim 9, whereinsaid process chamber comprises a lower wall and a side wall, the sidewall having a height of at most about four inches.
 12. The vacuumprocessing apparatus according to claim 11, wherein said process chamberis made of a single unit of plate stock having a thickness of about fourinches.
 13. The vacuum processing apparatus according to claim 12,wherein said plate stock is aluminum.
 14. The vacuum processingapparatus according to claim 11, wherein said plurality of pumping portsare located on the lower wall of said process chamber adjacent to aprocess chamber volume.
 15. The vacuum processing apparatus according toclaim 11, wherein three pumping ports are provided on the lower wall ofsaid process chamber symmetrically spaced about a chuck assemblyprovided within said process chamber.
 16. The vacuum processingapparatus according to claim 15, wherein three pumping cells areconnected to said process chamber, each one of said three pumping cellsbeing connected to a respective one of said three pumping ports.
 17. Thevacuum processing apparatus according to claim 11, wherein two pumpingports are provided on the lower wall of said process chambersymmetrically spaced about a chuck assembly on opposing sides thereof.18. The vacuum processing apparatus according to claim 17, wherein twopumping cells are connected to said process chamber, each one of saidtwo pumping cells being connected to a respective one of said twopumping ports.
 19. The vacuum processing apparatus according to claim10, further comprising means for reducing open volume within saidprocess chamber.
 20. The vacuum processing apparatus according to claim19, wherein said means for reducing open volume comprises a chamberliner configured to displace open volume within said process chamber.21. The vacuum processing apparatus according to claim 10, wherein saidprocess chamber facilitates the formation of plasma.
 22. A method ofmaking an improved process chamber, said method comprising the step of:making the process chamber with a lower wall and a side wall, the sidewall having a height of at most about four inches.
 23. The methodaccording to claim 22, wherein the process chamber is made of a singleunit of plate stock having a thickness of about four inches.
 24. Themethod according to claim 23, wherein the plate stock is aluminum. 25.The method according to claim 22, further comprising the step ofproviding in the process chamber at least one pumping port configured toreceive a pumping cell.
 26. The method according to claim 22, furthercomprising the step of providing in the process chamber a plurality ofpumping ports each configured to receive a pumping cell.
 27. The methodaccording to claim 26, further comprising the step of providing theplurality of pumping ports on the lower wall of the process chamberadjacent to a process chamber volume.
 28. The method according to claim26, further comprising the steps of: providing a chuck assembly in theprocess chamber; and providing three pumping ports on the lower wall ofthe process chamber symmetrically spaced about the chuck assembly. 29.The method according to claim 26, further comprising the steps of:providing an upper electrode to facilitate the formation of plasma inthe process chamber.
 30. The method according to claim 22, furthercomprising the step of providing in the process chamber a chamber linerconfigured to displace open volume within the process chamber.
 31. Amethod of making an improved process chamber, said method comprising thesteps of: providing a plurality of pumping ports in the process chamber;and connecting a respective pumping cell to each of the plurality ofpumping ports.
 32. The method according to claim 31, further comprisingthe step of making the process chamber with a lower wall and a sidewall, the side wall having a height of at most about four inches. 33.The method according to claim 32, further comprising the step of makingthe process chamber of plate stock having a thickness of about fourinches.
 34. The method according to claim 33, wherein the plate stock isaluminum.
 35. The method according to claim 32, further comprising thestep of making the process chamber comprising a molding process.
 36. Themethod according to claim 32, wherein said lower wall is a plate andsaid side wall is a rolled cylinder, further comprising the step ofmaking the process chamber comprising welding the lower wall to the sidewall.
 37. The method according to claim 32, further comprising the stepof providing the plurality of pumping ports on the lower wall of theprocess chamber adjacent to a process chamber volume.
 38. The methodaccording to claim 32, further comprising the steps of: providing achuck assembly in the process chamber; and providing three pumping portson the lower wall of the process chamber symmetrically spaced about thechuck assembly.
 39. The method according to claim 38, further comprisingthe step of connecting three pumping cells to the process chamber,wherein each one of the three pumping cells are connected to arespective one of the three pumping ports.
 40. The method according toclaim 32, further comprising the steps of: providing a chuck assembly inthe process chamber; and providing two pumping ports on the lower wallof the process chamber symmetrically spaced about the chuck assembly onopposing sides thereof.
 41. The method according to claim 40, furthercomprising the step of connecting two pumping cells to the processchamber, wherein each one of the two pumping cells are connected to arespective one of the two pumping ports.
 42. The method according toclaim 31, further comprising the step of providing in the processchamber a chamber liner configured to displace open volume within theprocess chamber.
 43. The method according to claim 31, furthercomprising the steps of: providing an upper electrode to facilitate theformation of plasma in the process chamber.